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For the birds: Innovations enable tracking of even small flying animals

  • Advances in satellite communications have revolutionized wildlife telemetry, yet tracking the movements of small animals, especially ones that fly, and marine species, which rarely break the ocean’s surface, has remained a challenge.
  • In a November 20th virtual meetup on next-generation wildlife tracking, three speakers introduced developments that have broadened telemetry’s reach to new species and new types of data being collected.
  • Recent innovations — including the ICARUS tracking system, hybridization of communications platforms, and miniaturization of sensors — are producing tiny solar-powered tracking tags and tags carrying various environmental sensors that function within private networks flexible enough to use the most efficient of several communications technologies available at a given site.

Animal tracking has revolutionized our study of animal movements and behavior.

Radio transmitter tags, followed by GPS and other satellite-based tags, placed on animals via a collar, harness, glue, or suction, use radio signals to transmit data from a transmitter in one place to receiving equipment somewhere else. They differ in how the signals are sent or received, the information obtained from the signals, and the energy needed to make the signals.

Ultra-high frequency (UHF) and  very-high frequency (VHF) radio tags are cheap, but researchers must physically tune receivers in to the various frequencies and manually determine each location’s coordinates. These processes take time and  money, thereby limiting the number of point locations that can be obtained for a given animal.

Standard GPS tracking collars like the one on this male jaguar in Brazil, are have been limited to larger, terrestrial species that can easily carry the weight of batteries needed to power the device. Recent developments in programmable tags, solar panels, and communications are enabling smaller tags for smaller animals. Image by Charles J. Sharp via Wikimedia Commons, CC 4.0.

Advances in communication systems, specifically transmission to and from satellites, have revolutionized wildlife tracking. GPS and other satellite-based tags have weighed more, costed more, and demanded more power than radio tags. Nevertheless, their automated collection of animals’ location coordinates has helped researchers more precisely determine home ranges, migration routes, and the relationships of these patterns to landscape features.

A virtual meetup hosted by the WILDLABS platform on November 20th entitled Next-generation wildlife tracking, featured three speakers who introduced developments that are broadening telemetry’s reach to new species and collecting new types of data.

Christian Rutz, president of the International Bio-Logging Society, described advances in positional tracking and data downloads, wireless sensor networks, on-board data processing and event-triggering, and animal-borne video and audio-loggers, that enable automated tracking of animals, such as birds, that fly or are too small to wear standard GPS tags.

A small ICARUS tag being placed on a bird. Screenshot image from YouTube video by ICARUS partner Max Planck Institute.

Rutz explained the potential of the ICARUS system, installed on the International Space Station (ISS) in August 2018, for tracking migratory patterns of flying animals. The proximity to Earth of the ISS (320 kilometers/199 miles) compared to that of the global Argos satellite (850 kilometers/528 miles) means radio transmitters on these tags can use weaker radio signals to communicate and thus be much smaller, as light as 5 grams (0.2 ounces). The solar-powered tags transmit only when the satellite is overhead, further reducing battery use.

A breakdown of the 5-gram ICARUS tracking tag. Screenshot image from YouTube video by ICARUS partner Max Planck Institute.

Other developments that have made tracking small creatures feasible include wireless networks of transceivers that log encounters between tagged individuals as well as from receiver stations. Rutz and colleagues have used these small tags (~10 grams) that communicate with each other to assess social behavior and reconstruct the movements of the birds. They have further observed bird behavior using programmable miniature video and audio loggers tiny enough for the animals to wear.

Virginie Perilhon, product manager at Xerius Tracking, explained her electronics company’s launch into wildlife conservation. In 2013, the firm developed a system to find tracking tags that have dropped off animals and then developed its own lightweight GPS/UHF tags with solar panels and remote access transmitters for falcon tracking in the Middle East.

Perilhon also described tools that combine several technologies. Her team is trialing a tracking system called BioLoc that allows a reserve or other landowner to create its own network that combines several communication platforms, depending on available connectivity. The network combines GPS, GSM (cell), UHF (radio), and Bluetooth to detect tags of up to 240 animals simultaneously with a 200-kilometer (124-mile) reach through line of sight.

Depiction of the tiny (5-10 gram) tracking tags and a solar-powered receiving station within a private closed BioLoc network. Screenshot image from webinar presentation by Virginie Perilhon.

When tagged animals are within a preset area, the tags communicate through the fine-scale network; when they leave, the tags connect with the global satellite-based Argos system to track their broad-scale movements.

Its small (5-gram/0.2-ounce) programmable tags powered by solar panels reach more than 20 kilometers (12 miles) and carry with GPS/UHF/Argos connection. The researcher can reprogram the tag or download the positional data remotely.

According to Perilhon, the uncertain schedule of satellites passing over and the (in)efficiency of batteries and solar panels were limitations her team was working to overcome.

Jake Levenson, a marine biologist for the U.S. Department of the Interior and director of Oceans Forward, an NGO helping countries develop affordable wildlife-related technology, spoke about capturing the expanding types of data telemetry is making available.

“Increasingly, telemetry is becoming a way to do more than study animals,” Levenson said. “Groups are putting all sorts of sensors on satellite tags that are able to tell us about the environment around them,” including temperature, water quality, or salinity for marine species.

A hawksbill sea turtle (Eretmochelys imbricata) off Maui, Hawaii with a GPS-linked satellite tag attached to its carapace. The tag allows U.S. National Oceanic and Atmospheric Administration (NOAA) researchers to track the turtle’s movements and critical habitat to recommend actions for the species’ recovery. Miniaturized sensors are increasingly included in these tags to measure water temperature, salinity, and quality. Image courtesy of Don McLeish, NOAA/NMFS/PIFSC, CC 2.0.

As sensors get smaller, scientists can collect more types of data with a single tag, Levenson said; however, the capture of these data has not advanced in the same way – a situation that, he said, was “ripe for disruption.”

“Tags have changed dramatically,” he added, “but the technology we use to track animals — the way we get data off them — with the exception of ICARUS recently, really hasn’t advanced much.” For example, satellite-based tags on air-breathing marine species only transmit when an animal is at the surface, and the error risk increases if that surface interval occurs when satellites are closer to the horizon.

Levenson and others seek to leverage technology to improve the transmission process without increasing cost. He recently partnered with colleagues at NASA to launch a next-generation animal tracking ideation challenge, which received 36 proposals, from participants from 25 countries, to do just that. The challenge will announce the winners of $30,000 in prizes on December 18, 2018. Levenson said the challenge gave the agencies a chance to formulate bigger-picture visions for telemetry, and that they expect to host another challenge in the future.

A large sail fish with its new tracking tag. NOAA uses the tags to assess movements and population dynamics of large pelagic fish. Image courtesy of Derke Snodgrass, NOAA/NMFS/SEFSC/SFD.

The WILDLABS virtual meetup series aims to encourage communication between users and developers of technology for conservation. It began in early November 2018, with a webinar highlighting three projects that deploy networked sensor technologies to help protected areas reduce poaching and human-wildlife conflict.

The third meetup, on big data in conservation, is planned for December 12 from 3-4pm GMT / 10-11am EST. The focus of this discussion shifts from data collection to management and processing, including databases and machine learning tools. You can register for it here.

Banner image of migrating geese, via Pexels, CC0.

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